1. Field of the Invention
The present invention generally relates to hand-held striking tools. More specifically, this invention is directed to an axe that resists recoil and imparts a more effective force per strike compared to prior art axes to reduce effort of use when the tool is struck against an object.
2. Description of the Related Art
Hand-held striking tools are among the oldest implements known to man. Nonetheless, inventors continually develop useful improvements to these tools that manufacturers continually incorporate into their designs for sale in the marketplace.
Specifically, many attempts have been made to reduce the undesirable effects of striking a tool against a workpiece. For example, over a century ago in U.S. Pat. No. 115,532, James M. Sears taught use of a flexible axe handle to prevent impact shock to the hands and to impart more force to the workpiece. Sears disclosed the axe handle as having a flexible joint consisting of an iron tenon, a wood grip, an iron hook portion screwed along a portion of the wood grip, and a rubber block disposed between the wood grip and iron tenon. The pivot axis of the flexible joint is defined by the hook of the iron hook portion being pivoted around a pivot portion of the iron tenon. The flexible joint is bolstered by a pair of steel side straps flexibly fastened across both the iron tenon portion and wood grip portion. Rivets extend through holes in the side plates and holes in the wood grip portion to immovably fasten the steel side straps to the wood grip portion. In contrast, rivets extend through holes in the side plates and slots in the iron tenon portion to pivotably fasten the steel side straps to the iron tenon portion. The slots are arcuately shaped and thereby permit the iron tenon portion to pivot about the pivot axis. While the Sears design may be effective to absorb shock of an axe strike, it is not clear how such absorption would enable greater impact to be imparted to a workpiece from the axe. Perhaps the absorption characteristic enables or encourages the user to exert more energy in any given swing. It is believed, however, that shock absorption in an axe would, by definition, impart somewhat less force to the workpiece since the energy that is being absorbed by the axe is not being imparted to the workpiece.
In another example, U.S. Pat. No. 1,045,145, E. O. Hubbard taught the use of a hammer having a cushioned head to reduce the shock of impact of the head with a workpiece such that the shock is absorbed and not imparted to a user""s hand. Hubbard discloses a hammer head having a hollow body with a rubber cushion disposed therein against which an internal head is positioned. An external head is positioned outside the hollow body and threadably fastens to the internal head. Thus, when the external head is struck against a workpiece the impact is imparted through the internal head and absorbed by the rubber cushion. Again, via absorption principles, the impact force on a workpiece is reduced and not enhanced.
Following the attempts of Sears and Hubbard to reduce impact shock, the prior art has suggested various designs for reducing rebound or recoil of a hammer, commonly referred to today as xe2x80x9cdead blowxe2x80x9d hammers. One of the earliest attempts, U.S. Pat. No. 2,451,217 to Heinrich, teaches use of an internal reactionary member disposed in the head of a hammer to absorb impact shock. Heinrich disclosed a hand hammer having a handle terminating in a hollow head. The hollow head includes a hollow internally threaded member, and a hollow externally threaded member that is threaded into the hollow internally threaded member, and a slug that is slidably disposed within the collective interior of the hollow head. Upon impact of the hollow head with a workpiece, the slug suddenly shifts in the direction of the strike from a rearward position in the hollow head to a forward position against the inside of one of the hollow members. Accordingly, the sudden shift of the slug tends to resist the force of the rebound and thereby cushions the force sufficiently to preserve all the power of the impact and yet keep the head from bouncing back from the workpiece. In actuality, however, the slug itself tends to bounce back and forth within the hollow head after impact, thereby causing undesirable vibration in the hand tool.
After Heinrich, a multitude of patents issued that addressed the shortcomings thereof. This inventive activity essentially involved replacing the slidable and bounceable slug of Heinrich with small particles. One of the first to do so was U.S. Pat. No. 2,604,914 to Kahlen. Kahlen addressed unsuccessful post-Heinrich efforts to use fine powder within a hollow head of a hammer to reduce hammer recoil and vibration. Kahlen claimed that powdered material tended to pack together within the hollow head thereby leading to undesirable results, and further claimed that using round shot resulted in oscillation after impact. Instead, Kahlen taught using irregularly shaped, rather than round, shot material disposed within a hollow head of a hammer to reduce hammer recoil. Specifically, Kahlen disclosed the hammer having a T-shaped hollow body having one branch of the T fastened to one end of a handle. The opposed ends of the T each have a striking head fastened thereto by way of an intermediate plug member. Between the plug members a chamber is defined for housing the irregularly-shaped shot.
In the mid-1970""s, U.S. Pat. Nos. 3,844,321 and 4,039,012 to William H. Cook taught various improvements to the basic Kahlen dead-blow hammer including unitarily casting such a hammer within a polymeric material to solve certain problems including hammer marring, tearing, and sparking as well as the short working life and difficulty in manufacturing such hammers. As a result, Cook disclosed different hammers, each having a handle member terminating in a hollow cylindrical head having a cavity with lead shot disposed therein. The hammers are entirely or predominantly encased within a urethane using molding techniques now well-known in the art of tool manufacture.
Unfortunately, neither Kahlen nor the Cook designs are reasonably capable of splitting wood in an efficient manner. Furthermore, the Kahlen/Cook design has a significant shortcoming. Presumably, and since there are no teachings to the contrary, the hollow headxe2x80x94by itselfxe2x80x94represents a relatively light hammer head compared with conventional solid forged hammer heads. It is, therefore, the lead shot that provides the mass with which to strike a workpiece. Thus, even though the ultimate impact force of the hammer may be typical, the initial impact of just the mass of the hollow head is relatively low. Thus, the lead shot may have the effect of reducing recoil of the hammer, but the lead shot does nothing to add extra impact power beyond the conventional mass of a conventional hammer.
More recently, in U.S. Pat. No. 5,261,164, Curtis L. Bellegante taught use of a locking swiveled axe to intensify the impact force of an axe. This invention includes a handle consisting of a main shaft, a swivel shaft, and a releasable latching device disposed therebetween. The main shaft includes a grip end and a connecting end distal the grip end, and the swivel shaft includes a blade attached at a blade end and a connecting end distal the blade end. The releasable latching device is located between the connecting ends of the main and swivel shafts and consists of a ball-lock-pin that enables the pivoting action of the axe and further consists of a spring-loaded latch.
In operation, a user presses the spring-loaded latch to free the swivel shaft from its locked upright position to an angled back position. Then, the axe is swung forward with sufficient force to accelerate the blade whereby the swivel shaft swings to a position aligned with the main shaft just before impact, such that the spring-loaded latch locks up to prevent the blade from reversing momentum upon impact with an object. Unfortunately, the Bellegante axe necessarily includes a collection of unnecessarily complex features including the ball-lock-pin, spring loaded latch, and catch grooves, which require lubrication. Moreover, to ensure that the swivel shaft locks in place just before impact, Bellegante evidently requires a user to adjust his swing from a typical full follow-through swing to a stop-action swing.
From the above, it can be appreciated that impact absorbing and dead-blow hand tools of the prior art are not fully optimized to provide a simpler, less costly hand tool that is truly capable of delivering an intensified impact and resisting impact recoil. Therefore, what is needed is a simple and relatively inexpensive dead-blow axe that delivers a relatively more intense impact and resists recoil upon impact.
According to the preferred embodiment of the present invention, there is provided an axe having a head, a handle, a rigid casing, and a shock-absorbing mass disposed within a portion of the ax. The head includes a blade end and a blunt end, wherein the handle integrally extends away from the blunt end and terminates in a grip portion. The rigid casing covers a portion of either or both of the head and handle, and the shock-absorbing mass is disposed within a chamber that is partially defined by the casing. Upon swinging the axe into impact with an object to be cut by the ax, the shock-absorbing mass suddenly shifts forward under the inertia of the swing to intensify the impact of the axe and to reduce the recoil of the ax.
The present invention is capable of successfully incorporating the benefits of dead-blow functionality into an axe such that improved impact and reduced recoil of the axe is achieved.
It is an object of the present invention to provide an axe having dead-blow functionality such that the recoil of the axe is reduced.
It is another object to provide an axe having such dead-blow characteristics that are enabled using relatively inexpensive design features and using well-known manufacturing processes.
It is still another object to eliminate or reduce the need to use a sledge hammer and wedge combination to split wood.
It is yet another object to achieve improved axe performance with the axe of the present invention compared to prior art axes of comparable size and weight.